In printed-value accounting systems, it is often necessary to provide complete secure housings which incorporate both a value-imprinting device, and all input devices related thereto, as well as accounting systems which provide for incrementing or decrementing values of accumulating registers in accordance with the value to be imprinted upon a substrate. The requirement of providing secure housings around all of this mechanism is both costly, space consuming, and provides certain security difficulties insofar as access to the various mechanisms are concerned. To avoid this problem, various attempts have been made to separate various functions from the secure housing in order to minimize the amount of equipment which must be contained within the secure housing. For example, in accordance with one well known procedure for processing mail, it is necessary for a user to purchase stamps at a Post Office, and to apply such stamps to an envelope or package at a later time. There is no need in such a process for the user to account for the postage to the Post Office, since this is effectively done by the Post Office at the time of the purchase.
In order to overcome the inconvenience of prepurchasing stamps and applying them to envelopes or packages, it is well known to employ a secure Postage Meter at the user's location. This procedure, however requires the purchase or rental by the user of a secure Postage Meter that simultaneously prints postal indicia on the envelope, and also accounts for the printed postage. The printer in such a Postage meter is necessarily secure, and the indicia must be in a proper form in accordance with Postal Regulations, to ensure that it can be read for verification purposes at the Post Office. In such a system, the presence of proper indicia on the mail piece is understood by the Post Office to show that the necessary postage has been paid for.
Speed of processing is improved by eliminating necessity of changing or re-setting print wheels. Economy is achieved by virtue of a design which eliminates the need for mechanics which change or re-set the print wheels. Ink jet printing such as found in U.S. Pat. No. 3,869,986 while useful in printing devices, are subject to clogging and are not as reliable as a simple stamp imprint device.
In an attempt to overcome these problems, it has been suggested in U.S. Pat. No. 4,934,846, issued Jan. 19, 1990 European Patent Application Publication No. 0376576, published Jul. 4, 1990, U.S. Pat. No. 4,796,193 issued Jan. 3, 1989, German Patent 2,193,468 May 15, 1991 and assigned to the assignee of the present inventors, to provide an unsecured mechanism for printing postage values on a mail piece or tape adapted to be applied to a mail piece. The printed postage values simulate postage stamps, in a certain sense, but they do not represent postage that has been paid for or accounted. As in the case of the use of conventional stamps, the value markings must be read at the Post Office and canceled. In addition, it is necessary for the Post Office itself to account for the value, for example to the account of an entity who has prepaid for the service and whose identification appears on the mail piece. Thus, while the arrangement may simplify the task of the user, it increases the required efforts of the Post Office. In addition, such a system does not readily permit the user to provide accounting, a feature which is often a requirement in modern postage-meter technology, as well as in any value accounting system wherein the user wishes to keep track of a single account as in conventional individual postage meters, or a multiple account database system with regard to specific sets of values imprinted upon documents.
While U.S. Pat. No. 4,796,193 shows placing a mark on the document, such reference does not show that such mark represents the source of the mark. Also, this reference calls for a manifest system, unlike the simpler stand-alone concept herein. The system of the above described references are accordingly not a value accounting system for indicating an accounted value, since it does not easily identify the source nor indicate in any manner that a proper accounting has been done. Elective verification of value accounting by identification of source and certification of accounting is useful both from a user viewpoint, and from an authority's viewpoint, should the value printing be employed in a value-accounting system which requires ultimate verification by the use of a central authority, such as the United States Postal Service. The same may also be applicable with regard to express mail and package delivery as well as other forms of delivery requiring prepaid delivery charges. With this system, verification need only be done on an elective or random basis, thus reducing the burden on central authority figures.
It is therefore desirable to provide a relatively simple means for validating and certifying accounting of printed values, such as postage or the like, printed by a printhead located in a non-secure environment, and securing only the accounting device which can also provide a unique observable and verifiable validation of accounting for later verification.